Expandable device for treatment of a stricture in a body vessel

ABSTRACT

An expandable and retrievable device for treatment of a stenotic lesion in a body vessel is disclosed. The device comprises a tubular portion including a proximal end and a distal end extending from the proximal end. The tubular portion has a lumen formed therethrough between the proximal and distal ends. The device further comprises an expandable member formed helically about the tubular portion. The expandable member is configured to helically close, defining a collapsed state for delivery of the device. The expandable member is configured to helically open, defining an expanded state for treatment of the stenotic lesion in the body vessel. The expandable member has at least one filter portion that helically extends from the tubular portion at a predetermined angle. This defines a proximally faced opening when the expandable member is in the expanded state.

BACKGROUND OF THE INVENTION

The present invention relates to medical devices and particularly thepresent invention relates to an expandable device for treating astricture in a body vessel.

Treatments for a stenotic lesion are continuously being improved. Oneexample is the treatment for carotid artery stenosis. Generally, carotidartery stenosis is the narrowing of the carotid arteries, the mainarteries in the neck that supply blood to the brain. Carotid arterystenosis (also called carotid artery disease) is a relatively high riskfactor for ischemic stroke. The narrowing is usually caused by plaquebuild-up in the carotid artery. Plaque forms when cholesterol, fat andother substances form in the inner lining of an artery. This formationprocess is called atherosclerosis.

Depending on the degree of stenosis and the patient's overall condition,carotid artery stenosis has been treated with surgery. The procedure(with its inherent risks) is called carotid endarterectomy, whichremoves the plaque from the arterial walls. Carotid endarterectomy hasproven to benefit patients with arteries substantially narrowed, e.g.,by about 70% or more. For people with less narrowed arteries, e.g., lessthan about 50%, an anti-clotting drug may be prescribed to reduce therisk of ischemic stroke. Examples of these drugs are anti-plateletagents and anticoagulants.

Carotid angioplasty is a more recently developed treatment for carotidartery stenosis. This treatment uses balloons and/or stents to open anarrowed artery. Carotid angioplasty is a procedure that can beperformed via a standard percutaneous transfemoral approach with thepatient anesthetized using light intravenous sedation. At the stenosisarea, an angioplasty balloon is delivered to predilate the stenosis inpreparation for stent placement. The balloon is then removed andexchanged via catheter for a stent delivery device. Once in position, astent is deployed across the stenotic area. If needed, an additionalballoon can be placed inside the deployed stent for post-dilation tomake sure the struts of the stent are pressed firmly against the innersurface of the vessel wall.

Currently, devices such as stents used for treatment of a stenosis aretypically permanent devices when deployed in a body vessel. In manysituations, when a stenosis condition has passed, the deployed stent cannot be removed from the patient. Thus, there is a need to provide aretrievable device, e.g., a stent, for treatment of a stenosis orstricture in a body vessel without compromising the cross-sectionalprofile of the device.

BRIEF SUMMARY OF THE INVENTION

The present invention generally provides an expandable and retrievabledevice for treatment of a stricture in a body vessel. The device has areduced cross-sectional profile and is configured to conform to thetortuosity of blood vessels. This provides the ability for retrieval andan enhanced flexibility for access to more tortuous lumen areas with abody vessel.

In one embodiment, the present invention provides an expandable devicefor treatment of a stenotic lesion in a body vessel. The devicecomprises a tubular portion including a proximal end and a distal endextending from the proximal end. The tubular portion has a lumen formedtherethrough between the proximal and distal ends. The device furthercomprises an expandable member formed helically about the tubularportion. The expandable member is configured to helically close,defining a collapsed state for delivery of the device. The expandablemember is configured to helically open, defining an expanded state fortreatment of the stenotic lesion in the body vessel. The expandablemember has at least one filter portion that helically extends from thetubular portion at a predetermined angle. This defines a proximallyfaced opening when the expandable member is in the expanded state.

In another embodiment, the present invention provides an assembly fortreatment of a stricture in a body vessel. The assembly comprises aninner catheter having a tubular body portion. The assembly furthercomprises an outer catheter having a distal end through which the innercatheter is disposed for deployment in the body vessel. The assemblyfurther comprises the expandable device coaxially disposed within theinner catheter for treatment of the stricture in the body vessel.

In another example, the present invention provides a method for treatinga stricture in a body vessel. The method comprises percutaneouslyintroducing an inner catheter in the body vessel. The inner catheter hasa tubular body portion. The method further comprises disposing theexpandable device for treatment of the stricture in the body vessel. Thedevice is in a collapsed state and is coaxially within the innercatheter. The method further comprises deploying the device in theexpanded state at the stricture of the body vessel to treat thestricture.

Further objects, features, and advantages of the present invention willbecome apparent from consideration of the following description and theappended claims when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an expandable device for treating a strictureof a body vessel in accordance with one embodiment of the presentinvention.

FIG. 2 is an enlarged view of the device of FIG. 1.

FIG. 3 a is a side view of an assembly for treating a stricture in abody vessel in accordance with one embodiment of the present invention.

FIG. 3 b is an exploded view of the assembly in FIG. 3 a.

FIG. 4 is a flowchart of a method for treating a stricture in a bodyvessel in accordance with one example of the present invention.

FIGS. 5 a-5 d are environmental views of treating a stricture with theexpandable device.

FIG. 5 e is an enlarged view of the expandable device in FIG. 5 d.

DETAILED DESCRIPTION OF THE INVENTION

The present invention generally provides an expandable device, e.g., astent, having a reduced cross-sectional profile and configured toconform to tortuosity of blood vessels, allowing for the device to bemore easily advanced through body vessels and providing an enhancedflexibility for access to more tortuous lumen areas within the bodyvessels. The device has a tubular portion and an expandable memberformed helically about the tubular portion. The expandable member has atleast one member portion, preferably a plurality of separate memberportions, helically extending from the tubular portion at apredetermined angle. The separate member portions allow the tubularportion to maintain its flexibility as it is disposed through a tortuousbody vessel. When helically closed, the device may be delivered througha body vessel. Upon deployment in a body vessel, the expandable memberself-expands and helically opens.

FIG. 1 illustrates an expandable device 10 for treating a stricture in abody vessel in accordance with one embodiment of the present invention.As shown, the device 10 comprises a tubular portion 12 about which anexpandable member 20 is formed. The expandable member 20 may behelically closed to define a collapsed state and helically opened todefine an opened state.

As mentioned above, the device 10 comprises a tubular portion 12 havinga first diameter D₁. As illustrated in FIG. 1, the tubular portion 12includes a proximal portion 14 and a distal portion 16 extending fromthe proximal portion 14. The tubular portion 12 is preferably a tubularmember for enhanced flexibility and to allow for a wire guide to beadvanced therethrough.

This may be accomplished by any suitable means such as by machining theexpandable member 20 helically around the tubular portion 12 disposedabout a mandrel. However, any other way of forming the expandable member20 helically about the tubular portion 12 may be used without fallingbeyond the scope or spirit of the present invention.

FIGS. 1 and 2 depict the device 10 further comprising an expandablemember 20 formed helically about the tubular portion 12. In thisembodiment, the expandable member 20 is configured to helically close,defining a collapsed state for delivery and retrieval of the device 10.Moreover, the expandable member 20 is configured to helically open todefine an expanded state for treating a stricture in the body vessel.The expandable member 20 occupies a second diameter D₂ that varies basedon the expanded and collapsed state thereof.

As shown, the expandable member 20 comprises at least one member portion30, preferably a plurality of member portions 30, each of which isintegrally formed with another member portion 30. Each member portion 30is helically formed and outwardly extends separately from the tubularportion 12 at a predetermined angle defining a proximally faced openingwhen the member is in an expanded state. In one embodiment, thepredetermined angle is between about 40 and 70 degrees and preferablybetween about 55 and 65 degrees.

As shown, each of the plurality of member portions 30 is in coaxialalignment with each other about the tubular portion 12. Preferably, eachmember portion 30 is helically formed integrally with the tubularportion 12 and separately extends therefrom. This allows the tubularportion 12 to maintain its flexibility with the first diameter D₁ foradvancement through tortuous areas within a body vessel.

The expandable member 20 and the tubular portion 12 are formed along alongitudinal axis. The expandable member 20 may be helically closed inthe collapsed state when the tubular portion 12 or the expandable member20 is rotated about the longitudinal axis in a first direction. Theexpandable member 20 may be helically opened in the expanded state whenthe tubular portion 12 or the expandable member 20 is rotated about thelongitudinal axis in a second direction.

As mentioned above, the device may be made of shape memory material, ormay be configured to have shape memory defining the predetermined shapethereof in the deployed state. For example, the device may be comprisedof any suitable material such as a pre-configured polymeric material,superelastic material, stainless steel wire,cobalt-chromium-nickel-molybdenum-iron alloy, or cobalt-chrome alloy. Inone example, the device may be made of pre-configured polymeric materialwhich takes on a predetermined shape, e.g. helical, when in the expandedstate.

It is understood that the device may be formed of any other suitablematerial that may result in a self-opening or self-expanding device,such as shape memory materials or alloys. Shape memory alloys have thedesirable property of becoming rigid, i.e., returning to a rememberedstate, when heated above a transition temperature. A shape memory alloysuitable for the present invention is Ni—Ti available under the morecommonly known name Nitinol. When this material is heated above thetransition temperature, the material undergoes a phase transformationfrom martensite to austenic, such that material returns to itsremembered state. The transition temperature is dependent on therelative proportions of the alloying elements Ni and Ti and the optionalinclusion of alloying additives.

In one example, the device is made from material including Nitinol witha transition temperature that is slightly below normal body temperatureof humans, which is about 98.6° F. Thus, when the device 10 is deployedand exposed to normal body temperature, the alloy of the device willtransform to austenite, that is, the remembered state, which for oneembodiment of the present invention is the expanded state when deployedin the body vessel. To remove the device, the device is cooled totransform the material to martensite which is more ductile thanaustenite, making the device more malleable. As such, the device can bemore easily collapsed and pulled into a lumen of a catheter for removal.

FIGS. 3 a and 3 b depict an assembly 40 for treatment of a stricture ina body vessel in accordance with another embodiment of the presentinvention. As shown, the assembly 40 comprises an inner catheter 42having a tubular body 44. In this embodiment, the assembly 40 comprisesthe expandable device mentioned above. The tubular body 44 is preferablymade of soft flexible material such as silicon or any other suitablematerial. In this embodiment, the catheter 42 includes an inner lumen.The inner lumen is formed therethrough for percutaneous guidance throughthe body vessel.

As shown, the assembly 40 further includes an outer catheter 52 having adistal end 54 through which the inner catheter 42 is disposed fordeployment in the body vessel. The outer catheter 52 is preferably madeof a soft, flexible material such as silicon or any other suitablematerial. Generally, the outer catheter 52 further has a proximal end 56and a plastic adaptor or hub 58 to receive the expandable device andinner catheter 42 to be advanced therethrough. The size of the outercatheter 52 is based on the size of the body vessel in which itpercutaneously inserts, and the size of the inner catheter 42.

As shown, the assembly 40 may also include a wire guide 60 configured tobe percutaneously inserted within the vasculature to guide the outercatheter 52 to a location proximal to a stricture in a body vessel. Thewire guide 60 provides the outer catheter 52 (and inner catheter 42) apath during insertion within the body vessel. The size of the wire guide60 is based on the inside diameter of the outer catheter 52.

As shown, the expandable device is coaxially disposed through the innerlumen of the inner catheter 42 prior to treatment of the stricture inthe body vessel. The expandable device is guided through the inner lumenpreferably from the hub 58 and distally beyond the inner catheter 42,exiting from the distal end of the inner catheter 42 to a locationwithin the vasculature upstream of the stricture to be stented.

In this embodiment, the apparatus further includes apolytetrafluoroethylene (PTFE) introducer sheath 64 for percutaneouslyintroducing the wire guide 60 and the outer catheter 52 in a bodyvessel. Of course, any other suitable material may be used withoutfalling beyond the scope or spirit of the present invention. Theintroducer sheath 64 may have any suitable size, e.g., between aboutthree-french to eight-french. The introducer serves to allow the innerand inner catheters 42 to be percutaneously inserted to a desiredlocation in the body vessel. The introducer sheath 64 receives the outercatheter 52 and provides stability to the inner catheter at a desiredlocation of the body vessel. For example, the introducer sheath 64 isheld stationary within a common visceral artery, and adds stability tothe outer catheter 52, as the outer catheter 52 is advanced through theintroducer sheath 64 to a dilatation area in the vasculature.

When the distal end 54 of the outer catheter 52 is at a locationdownstream of the dilatation area in the body vessel, the inner catheter42 is inserted therethrough to the dilatation area. The device 10 isthen loaded at the proximal end of the inner catheter 42 and is advancedthrough the inner lumen thereof for deployment through its distal end.In this embodiment, the proximal stem is used to mechanically advance orpush the device 10 through the catheter.

FIG. 4 illustrates a flow chart depicting one method 110 for treating astricture in a body vessel (see FIG. 5 a), implementing the assemblymentioned above. The method comprises percutaneously introducing aninner catheter in the body vessel in box 112. Introduction of the innercatheter may be performed by any suitable means or mechanism. Asmentioned above, an introducer sheath and a wire guide may be used toprovide support and guidance to the inner catheter. For example, thewire guide may be percutaneously inserted through the introducer sheathto the stricture in the body vessel. The inner catheter may then beplace over the wire guide for percutaneous guidance and introduction tothe stricture.

The method 110 further comprises disposing the expandable devicecoaxially within the inner catheter in box 114. The device may bedisposed coaxially within the inner catheter before or afterpercutaneous insertion of the inner catheter. Preferably, the expandablemember is disposed along a longitudinal axis. For example, once theinner catheter is placed at the stricture of the body vessel, the wireguide may be removed therefrom, and the device may then be disposedwithin the inner catheter for guidance and introduction in the bodyvessel. In the collapsed state, the device may then be advanced distallypast the inner catheter in the body vessel (see FIG. 5 b).

As mentioned above, the expandable member is helically closed in thecollapsed state when the tubular portion is rotated about thelongitudinal axis in a first direction and the expandable member ishelically opened in the expanded state when the tubular portion isrotated about the longitudinal axis in a second direction.

The method 110 further includes deploying the device in the expandedstate in box 116 (see also FIG. 5 c). This may be accomplished bypushing the device by any suitable means such as a pusher. In thisexample, the device is self-expanding and is configured to turn about afirst direction relative to the tubular portion to helically open andtreat the stricture in the body vessel. In the expanded state, the openend of each member portion is expanded to a proximally facing concaveshape to engage the body vessel for stenting. In this embodiment, eachmember portion extends from the tubular portion at an angle betweenabout 40 and 70 degree (see FIGS. 5 d and 5 e). As desired, additionalinner catheters may be used for primary and post-dilatation treatment ofthe stricture.

The method 110 further comprises closing the device in the collapsedstate in the body vessel by rotating the tubular portion in the firstdirection and retrieving the device in the collapsed state in the innercatheter.

While the present invention has been described in terms of preferredembodiments, it will be understood, of course, that the invention is notlimited thereto since modifications may be made to those skilled in theart, particularly in light of the foregoing teachings.

The invention claimed is:
 1. An assembly for treatment of a stricture ina body vessel, the assembly comprising: an inner catheter having atubular body portion; an outer catheter having a distal end throughwhich the inner catheter is disposed for deployment in the body vessel;and an expandable device coaxially disposed within the inner catheterfor treatment of the stricture in the body vessel, the devicecomprising: a tubular portion including a proximal end and a distal endextending from the proximal end, the tubular portion having a lumenformed therethrough between the proximal and distal ends, the tubularportion having a longitudinal axis, wherein the tubular portionmaintains flexibility as it is disposed through a tortuous body vessel;and an expandable member formed helically about the tubular portion in aplurality of member portions arranged in continuous windings, theexpandable member formed integrally with the tubular portion, theexpandable member being configured to helically close, defining acollapsed state for delivery of the device, the expandable member beingconfigured to helically open, defining an expanded state, in which theexpandable member forms an outermost periphery of the expandable device,for treatment of the stenotic lesion in the body vessel, the pluralityof member portions helically extending from the tubular portion at apredetermined angle at the outermost periphery defining a proximallyfaced opening having a concave shape with the predetermined angleforming a greater opening angle than an opening angle adjacent thetubular member when the expandable member is in the expanded state, thepredetermined angle being between about 40 and 70 degrees, the pluralityof member portions having a solid one-piece construction.
 2. Theassembly of claim 1 further comprising: an introducer sheath throughwhich the outer catheter is inserted for percutaneous insertion to thebody vessel; and a wire guide introducible through the introducer sheathto the body cavity for guidance of the inner and outer catheters to thebody cavity.
 3. The assembly of claim 1 wherein the predetermined angleis between about 55 and 65 degrees.
 4. The assembly of claim 1 whereinthe opening of each member portion has an outer diameter, the outerdiameter increasing distally longitudinally relative to the tubularportion to define the expandable member having a distally flaredprofile.
 5. The assembly of claim 1 wherein the expandable member isformed by machining the expandable member helically around the tubularportion.
 6. A method for treating a stricture in a body vessel, themethod comprising: percutaneously introducing an inner catheter in thebody vessel, the inner catheter having a tubular body portion; disposingan expandable device for treatment of the stricture in the body vessel,the device being in a collapsed state coaxially within the innercatheter, the device comprising: a tubular portion including a proximalend and a distal end extending from the proximal end, the tubularportion having a lumen formed therethrough between the proximal anddistal ends, the tubular portion having a longitudinal axis, wherein thetubular portion maintains flexibility as it is disposed through atortuous body vessel; and an expandable member formed helically aboutthe tubular portion in a plurality of member portions arranged incontinuous windings, the expandable member formed integrally with thetubular portion, the expandable member being configured to helicallyclose, defining a collapsed state for delivery of the device, theexpandable member being configured to helically open defining anexpanded state, in which the expandable member forms an outermostperiphery of the expandable device, for treatment of the stenotic lesionin the body vessel plurality of member portions helically extending fromthe tubular portion at a predetermined angle at the outermost peripherydefining a proximally faced opening having a concave shape with thepredetermined angle forming a greater opening angle than an openingangle adjacent the tubular member when the expandable member is in theexpanded state, the predetermined angle being between about 40 and 70degrees, the plurality of member portions having a solid one-piececonstruction; and deploying the device in the expanded state at thestricture of the body vessel to treat the stricture.
 7. The method ofclaim 6 further comprising: closing the device in the collapsed state inthe body vessel by rotating the tubular portion in the first direction;and retrieving the device in the collapsed state in the inner catheter.8. The method of claim 6 wherein the predetermined angle is betweenabout 55 and 65 degrees.
 9. The method of claim 6 wherein the at leastone member portion is a plurality of member portions, such that thetubular portion maintains its flexibility as it is disposed through atortuous body vessel.
 10. The method of claim 9 wherein the opening ofeach member portion has an outer diameter, the outer diameter increasingdistally longitudinally relative to the tubular portion to define theexpandable filter having a distally flared profile.
 11. The method ofclaim 9 wherein each of the member portions separately extends from thetubular portion.
 12. A method for treating a stricture in a body vessel,the method comprising: percutaneously introducing an inner catheter inthe body vessel, the inner catheter having a tubular body portion;disposing an expandable device for treatment of the stricture in thebody vessel, the device being in a collapsed state coaxially within theinner catheter, the device comprising: a tubular portion including aproximal end and a distal end extending from the proximal end, thetubular portion having a lumen formed therethrough between the proximaland distal ends, the tubular portion having a longitudinal axis, whereinthe tubular portion maintains flexibility as it is disposed through atortuous body vessel; and an expandable member formed helically aboutthe tubular portion in a plurality of conical member portions arrangedin continuous windings, the expandable member formed integrally with thetubular portion, the expandable member being configured to helicallyclose, defining a collapsed state for delivery of the device, theexpandable member being configured to helically open defining anexpanded state, in which the expandable member forms an outermostperiphery of the expandable device, for treatment of the stenotic lesionin the body vessel, the plurality of member portions helically extendingfrom the tubular portion at a predetermined angle at the outermostperiphery defining a proximally faced opening having a concave shapewith the predetermined angle forming a greater opening angle than anopening angle adjacent the tubular member when the expandable member isin the expanded state, the predetermined angle being between about 40and 70 degrees, the plurality of conical member portions having a solidone-piece construction; and deploying the device in the expanded stateat the stricture of the body vessel to treat the stricture.
 13. Themethod of claim 12 wherein the predetermined angle is between about 55and 65 degrees.
 14. The assembly of claim 12 wherein the opening of eachmember portion has an outer diameter, the outer diameter increasingdistally longitudinally relative to the tubular portion to define theexpandable filter having a distally flared profile.
 15. The method ofclaim 12 further comprising: closing the device in the collapsed statein the body vessel by rotating the tubular portion in the firstdirection; and retrieving the device in the collapsed state in the innercatheter.